The significance of this proposal is that it focuses on cardiovascular diseases which represent a leading cause of mortality in industrialized nations. Atherosclerosis preferentially develops in regions of the arterial tree with branches and curvatures where blood flow is disturbed and shear stress is low and non- uniform. There is increasing evidence that laminar blood flow with high shear stress modulates gene expression in endothelial cells (ECs) to protect against atherosclerosis, inflammation and coagulation, and that disturbed flow upregulates proatherosclerotic, proinflammatory, and procoagulant genes. It has long been suspected that human cytomegalovirus (HCMV) infection is a risk factor for vascular disease such as atherosclerosis and restenosis following angioplasty. The key question is what is the mechanism underlying HCMV's role in the disease process? Many studies have shown that HCMV infection induces proatherogenic gene expression in ECs, smooth muscle cells and monocytes/macrophages, but all these studies were performed in static cell culture, where there is no flow or shear stress. The Deborah Spector lab is the first t study HCMV infection of aortic ECs exposed to varying conditions of flow and shear stress. We hypothesize that flow conditions affect HCMV interaction with ECs and that this in turn modulates the EC functions and interactions with leukocytes, and smooth muscle cells to lead to lesion formation. Detailed knowledge of HCMV pathogenesis as well as in vivo animal models are required in order to address questions regarding the HCMV infection in EC inflammation. The novelty of this proposal is that it addresses the roles of HCMV infection and flow dyamics in atherosclerosis by an interdisciplinary approach. It brings together the extensive expertise in the Deborah Spector lab on molecular and cellular biology of HCMV and MCMV, the broad experience in the Stephen Spector lab on HCMV pathogenesis and translational medicine, and the vast knowledge and technical expertise of Joseph Witztum on the in vivo pathogenesis of atherosclerosis to test our hypothesis and assess the potential role of HCMV in atherosclerosis. Three Specific Aims are proposed. In Aim 1, we will determine the bi-directional interactions between HCMV and ECs under high vs. low shear stress (HSS vs. LSS). In Aim 2, we will determine the effect of HCMV infection of ECs on adhesion and transendothelial migration of Immunologically primed and na?ve PBMCs under conditions of HSS and LSS. In Aim 3, we will utilize in vivo studies to define the impact of MCMV on the ApoE-/- mouse model of atherosclerosis. The long- term objective of this proposal is to provide novel insights into the pathogenesis of atherosclerosis. Accomplishment of this goal will facilitate the development of new strategies designed to prevent and treat atherosclerotic disease.